1. Field of Invention
The present invention relates to the field of antenna technology, and in particular to a chip incorporating antenna function and a wireless device using such chip incorporating antenna function.
2. Description of Prior Art
Antenna is an indispensable part of a wireless device and usually present as a separate element. Due to its various advantages, such as convenient in feed point, small in weight, cheap in price, excellent in mobility and less radiation to human body, a built-in antenna has recently gained rapid development and wide application, and a growing number of mobile wireless devices, such as client wireless network card of WLAN (Wireless Local Area Network), cell phone, PDA (Personal Digital Assistant) device and receiver of GPS (Global Positioning System), are operating with such built-in antenna.
An introduction will now be given to two typical implementations of the conventional built-in antenna.
(1) A Unipole Antenna Encircling A Chip
Referring to FIG. 1 which is a schematic diagram of the first implementation of a built-in antenna.
Such antenna acts as a loop antenna since it encircles the chip. According to certain principle in physics, if there is any alternating current flowing through a loop conducting line, magnetic flux is generated within the loop, and the alternating magnetic field gives rise to an electric field, which may disturb circuits on the chip. In addition, a loop antenna is generally low in efficiency, and therefore N (N is an integer greater than 1) turns of such antenna are often used for efficiency enhancement, which may accordingly increase the radiation resistance by a multiple of N2 and thus the disturbance to the adjacent chip circuits.
(2) An Antenna Positioned In Proximity of A Chip
Referring to FIG. 2 which is a schematic diagram of the second implementation of the built-in antenna.
Such implementation expands the overall area of the chip to such a considerable extent that it cannot meet the requirement of smallness in designing a modern wireless device. Also, since the antenna is positioned in the same plane as the chip, the disturbance to the chip cannot be avoided whether the antenna is omnidirectional or unidirectional.